Cutting mills have been known and used to comminute plastic wastes and corresponding cuttable materials in the form of chunks, hollow bodies, films and profiled materials, but also natural and synthetic rubber, vulcanized rubber, cable wastes, glass fiber wastes, leather or paper.
A drum-like cutting chamber as a stator surrounds a cutting rotor, which is arranged concentrically in the cutting chamber and beyond the outer circumference of which radially arranged cutting knives project with their outer ends, between which and the wall of the cutting chamber a cutting gap is located. The cutting knives arranged uniformly on the circumference of the rotor are radially adjustable in relation to the rotor in order to set the width of the cutting gap.
One section of the cutting chamber wall is designed as a screen, through which the cut material enters a chamber, from which it is removed from the mill, e.g., by drawing off, for further use. The screen forms a sizing means, because the mesh size of the screen determines when the cut material has reached the intended final smallness. Cut material below an intended limit value leaves the cutting mill through the screen for removal from the mill, while the material above the limit value rotates in the cutting mill and is subjected to the action of the knives until it can pass through the screen because of the smaller size it has reached.
Prior-art cutting mills of this design have hitherto been developed based on the criteria reliability in continuous operation, economical operation due to high performance and low energy consumption as well as low maintenance requirements.
The present invention is based on the recognition of shortcomings of such mills, which are caused by the sizing means. Even though the screen as a section of the cutting chamber wall is a simple component, a changeover of the mill to another degree of size reduction of the material to be cut is not possible with it because of the lack of variability of the mesh size and the replacement of the screen with a screen of a different mesh size or because the screen has reached its service life is complicated and time-consuming and means a long down time of the machine.
The object of the present invention is to propose a cutting mill which has marked advantages over the prior-art cutting mills concerning the sizing means.
The essence of the present invention is above all that in an otherwise known cutting mill, the sizing means is a rotating sizing means, which is associated with the cutting rotor and stator in a common housing.
The present invention offers the advantage that the cutting means, on the one hand, and the sizing means, on the other hand, are components of a single device, but the components are independent from one another to the extent that the sizing means can be adapted to the particular operating conditions substantially better than in the state of the art, and the replacement of a less sizing means with a more suitable one may be possible in a relatively simple manner.
A preferred embodiment of the present invention will be described below on the basis of the drawing.